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5.1.3 General flowchart
The multi-line display processing routine consists of initialization processing routine, V
routine, and CRT interrupt processing routine.
(1) Initialization processing routine
This routine is used to initialize to cause a CRT interrupt.
Multi-line display start
Initialization
CRTE (bit4 at address 00FE
CC (address 00EA
P5D (address 00CB
CRTP (address 00EC
CO0 (address 00E6
CO1 (address 00E7
CO2 (address 00E8
CO3 (address 00E9
Block 1 display RAM ←
Display character (blank) of block 1 (addresses 0600
Character color (no output) of block 1 (addresses 0680
CV1 (address 00E1
Vertical display start position of the 11th line (block 1)
Block 2 display RAM ←
Display character (blank) of block 2 (addresses 0620
Character color (no output) of block 2 (addresses 06A0
CV2 (address 00E2
Vertical display start position of the 12th line (block 2)
CS (address 00E4
MD (address 00E5
HR (address 00E0
CK (address 00ED
Line counter
F_VSYNC
Fig. 5.1.3 Flowchart of initialization processing routine
CRTE :
Bit 4 of interrupt control register 1
<CRT interrupt enable bit>
CRTR :
Bit 4 of interrupt request register 1
<CRT interrupt request bit>
CS :
Character size register
HR :
Horizontal position register
←"0"
)
16
←"00000000
"
)
2
16
←"00000000
"
)
2
16
←"00000000
"
)
2
16
←"00001000
" (red)
)
2
16
←"00000010
" (blue)
)
2
16
←"00001110
" (white)
)
2
16
←"00000110
" (cyan)
)
2
16
)←
16
)←
16
←"00000000
)
2
16
←"00000101
)
16
2
←"XXXXXXXX
)
16
←"00000010
)
16
2
←"0"
←"1"
END
7220 Group User's Manual
5.1 Example of multi-line display
Disable only CRT interrupt
All blocks display off
Select R/G/B/OUT1
H
/V
SYNC
R/G/B/OUT1 output polarity : positive polarity output
Color register 0 : red
Color register 1 : blue
Color register 2 : white
Color register 3 : cyan
to 0617
)
16
16
to 0697
)
16
16
to 0637
)
16
16
to 06B7
)
16
16
"
Character size : minimum size
"
Border output
"
Set a horizontal display start position
2
"
Set display clock
Enable CRT interrupt in synchronized
with the next V
Note: This routine is not interrupt
processing routine.
APPLICATION
interrupt processing
SYNC
Line counter :
Counter RAM for line counting
CV1, CV2 :
Vertical position registers 1, 2
P5D :
Port P5 direction register
CRTP :
CRT port control register
CC :
CRT control register
CO0 to CO3 :
Color registers 0 to 3
F_VSYNC :
V
flag
SYNC
MD :
Border selection register
CRT clock selection register
CK :
input polarity : positive polarity input
SYNC
SYNC
5-3
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